redneckgaijin

Nero Wolfe might have been right... that is, about it being impossible to think properly on an empty stomach.

A Scientific American article describes the complex network of nerves in the digestive system as "a second brain".

The second brain informs our state of mind in other more obscure ways, as well. "A big part of our emotions are probably influenced by the nerves in our gut," Mayer says. Butterflies in the stomach—signaling in the gut as part of our physiological stress response, Gershon says—is but one example. Although gastrointestinal (GI) turmoil can sour one's moods, everyday emotional well-being may rely on messages from the brain below to the brain above. For example, electrical stimulation of the vagus nerve—a useful treatment for depression—may mimic these signals, Gershon says.

(emphasis mine)